9 c++filt

The C++ and Java languages provide function overloading, which means
that you can write many functions with the same name, providing that
each function takes parameters of different types. In order to be
able to distinguish these similarly named functions C++ and Java
encode them into a low-level assembler name which uniquely identifies
each different version. This process is known as mangling. The
c++filt1
program does the inverse mapping: it decodes (demangles) low-level
names into user-level names so that they can be read.

Every alphanumeric word (consisting of letters, digits, underscores,
dollars, or periods) seen in the input is a potential mangled name.
If the name decodes into a C++ name, the C++ name replaces the
low-level name in the output, otherwise the original word is output.
In this way you can pass an entire assembler source file, containing
mangled names, through c++filt and see the same source file
containing demangled names.

You can also use c++filt to decipher individual symbols by
passing them on the command line:

c++filt symbol

If no symbol arguments are given, c++filt reads symbol
names from the standard input instead. All the results are printed on
the standard output. The difference between reading names from the
command line versus reading names from the standard input is that
command line arguments are expected to be just mangled names and no
checking is performed to separate them from surrounding text. Thus
for example:

c++filt -n _Z1fv

will work and demangle the name to “f()” whereas:

c++filt -n _Z1fv,

will not work. (Note the extra comma at the end of the mangled
name which makes it invalid). This command however will work:

echo _Z1fv, | c++filt -n

and will display “f(),”, i.e., the demangled name followed by a
trailing comma. This behaviour is because when the names are read
from the standard input it is expected that they might be part of an
assembler source file where there might be extra, extraneous
characters trailing after a mangled name. For example:

.type _Z1fv, @function

-_

--strip-underscores

On some systems, both the C and C++ compilers put an underscore in front
of every name. For example, the C name foo gets the low-level
name _foo. This option removes the initial underscore. Whether
c++filt removes the underscore by default is target dependent.

-n

--no-strip-underscores

Do not remove the initial underscore.

-p

--no-params

When demangling the name of a function, do not display the types of
the function's parameters.

-t

--types

Attempt to demangle types as well as function names. This is disabled
by default since mangled types are normally only used internally in
the compiler, and they can be confused with non-mangled names. For example,
a function called “a” treated as a mangled type name would be
demangled to “signed char”.

-i

--no-verbose

Do not include implementation details (if any) in the demangled
output.

-s format

--format=format

c++filt can decode various methods of mangling, used by
different compilers. The argument to this option selects which
method it uses:

auto

Automatic selection based on executable (the default method)

gnu

the one used by the gnu C++ compiler (g++)

lucid

the one used by the Lucid compiler (lcc)

arm

the one specified by the C++ Annotated Reference Manual

hp

the one used by the HP compiler (aCC)

edg

the one used by the EDG compiler

gnu-v3

the one used by the gnu C++ compiler (g++) with the V3 ABI.

java

the one used by the gnu Java compiler (gcj)

gnat

the one used by the gnu Ada compiler (GNAT).

--help

Print a summary of the options to c++filt and exit.

--version

Print the version number of c++filt and exit.

Warning:c++filt is a new utility, and the details of its
user interface are subject to change in future releases. In particular,
a command-line option may be required in the future to decode a name
passed as an argument on the command line; in other words,

c++filt symbol

may in a future release become

c++filt optionsymbol

Footnotes

[1] MS-DOS does not allow + characters in file names, so on
MS-DOS this program is named CXXFILT.